In the past several years, speeding-up of optical disk devices has proceeded, and 12×-speed CLV (Constant Linear Velocity) drives and maximum-24×-speed CAV (Constant Angular Velocity) drives have come along. With this speeding-up, allowable losses from heat become insufficient in conventional driver ICs, such as spindle driver ICs, actuator driver ICs and traverse driver ICs. This problem is dealt with by adding a heat dissipating plate or the like to a driver IC to control heat generation of the driver IC, arranging an air blowing means at an optical disk driving part to control heat generation as disclosed in Japanese Published Patent Application No. Hei. 9-265772, or employing a pattern design with a high heat radiation efficiency in PCB design, and in the case of an eccentric disk, by adopting a method of reducing the number of revolutions of the disk or the like.
Further, when there are constraint conditions on the driver IC, the heat dissipating plate for suppressing heat generation or the like cannot be added, and thus this problem is dealt with by using a driver IC of power package specifications whose allowable loss from heat is large or preventing the disk from being rotated at high speed.
In a case where the allowable loss of the driver IC due to heat is exceeded even though the above-described measures for suppressing heat generation are taken, in order to prevent the resultant breakdown of the driver IC or the like, the driver IC is provided with a thermal shutdown function, whereby the operation of the driver IC is stopped forcibly when the junction temperature as a chip temperature of the driver IC reaches a predetermined temperature.
However, when speeding-up of the optical disk device is to be further progressed in the future, the allowable loss of the conventional driver IC due to heat is insufficient, resulting in breakage of the driver IC. That is, due to the further speeding-up of the optical disk device, in partially with regard to eccentric disks or the like, it is required that the acceleration sensitivity of an actuator in a pickup should be increased more than ever, and face wobbling or eccentricity of a disk becomes more serious with the speeding-up, resulting in a severe heat generation of an actuator driver IC. Further, the change in the number of revolutions of the disk also becomes larger, and accordingly, heat generation in a spindle driver IC due to repetition of forced acceleration or forced deceleration of a spindle motor, or heat generation in a traverse driver IC due to high-speed movement of a traverse (thread) becomes severe.
When the driver IC is provided with the thermal shutdown function, the driver IC can be protected from breakage due to heat generation, but the optical disk device becomes uncontrollable while the thermal shutdown function is being operated.
The present invention is made to solve the above-mentioned problems and has for its object to provide an optical disk device which can exert a control for efficiently suppressing heat generation before driving of the optical disk device is impeded by heat generation of a driver IC for driving a recording/reproduction driving system of the optical disk device, and can perform a fast and stable operation within an allowable capacity of the driver IC.